sekio
Bluelight Crew
There is indeed less gravity at the center of the earth. (Well, stuff would experience less or no gravitational force... there's still gravity, but it all cancels out.) If you imagine a non-colliding particle subject to gravity (neutrino?) at the surface, the whole planet is pulling it one direction (into the centre of mass). As it moves through the planet going deeper, there is more and more of the planet "behind" it which exerts a force pulling away from the centre, and eventually when it reaches the center of the earth, there is an equal amount of mass on every side of the particle, so the gravitational force vectors all cancel out..
The upshot of this is that if you were able to punch a hole directly through the earth, and drop something down it, it would eventually be suspended in the exact middle of the planet. (Assuming a spherical earth and other stuff which isn't strictly true).
http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/earthole.html
The upshot of this is that if you were able to punch a hole directly through the earth, and drop something down it, it would eventually be suspended in the exact middle of the planet. (Assuming a spherical earth and other stuff which isn't strictly true).
http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/earthole.html
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